[FFmpeg-devel] [Patch] vf_edgedetect: properly implement double_threshold()

[Valery Kot]

On Mon, Jun 22, 2020 at 12:57 PM Moritz Barsnick <barsnick at gmx.net> wrote:
>
> On Mon, Jun 22, 2020 at 09:58:42 +0200, Valery Kot wrote:
> > Thanks for feedback. Updating FATE tests is a bridge too far for me. I
> > can't even build FFmpeg itself at the moment, say nothing about
> > setting up the test environment and finding out how it works. Could
> > you please do this update for me?
>
> Are you saying you analyzed this issue in the source code, but have
> not had a chance to check whether the change really fixes the output?
> [*]

I tested master build from Zeranoe to confirm that there is a bug
(modifying low threshold changes nothing in output). Then I modified
double_threshold() function and tested it locally in a unit test (in
my own testbed).

>
> Once you *do* understand how to build ffmpeg, you can follow the fate
> instructions here:
> https://ffmpeg.org/fate.html#Using-FATE-from-your-FFmpeg-source-directory
>
> You don't actually need to add a new fate test in this case, but submit
> the changed reference output with your patch (assuming that the changed
> output is really correct!).

I am working on Windows, and don't have build environment for FFmpeg
at this moment. As this is not a pressing issue for me, I don't want
to spend time on it. I was just developing my own Canny filter
implementation and noticed that FFmpeg edge detector is
underperforming (quality wise). I could've do nothing, or just sent a
bug report, but chose to send this patch as a contribution to the
community.

>
> Cheers,
> Moritz
>
> [*] I'm not saying that someone couldn't do that for you instead, if
>     they are willing.